Current demands for high density and performance associated with ultra large scale integration of fabricated devices require submicron features, increased transistor and circuit speeds, and improved reliability. As semiconductor processes progress, pattern dimensions such as line width, and other types of critical dimensions, are continuously shrunken. Such demands require formation of device features with high precision and uniformity, which, in turn, necessitates careful monitoring of the fabrication process, including frequent and detailed inspections and metrology operations related to the devices while they are still in the form of semiconductor wafers.
The term “specimen” used in this specification should be expansively construed to cover any kind of wafer, masks, and other structures, combinations and/or parts thereof used for manufacturing semiconductor integrated circuits, magnetic heads, flat panel displays, and other semiconductor-fabricated articles.
The terms “inspection” and “Metrology” alternately used in this specification should be expansively construed to cover any kind of measuring characteristics and features in a specimen provided by using measurement tools during or after manufacture of the specimen to be inspected. By way of non-limiting example, the metrology process can include generating a measurement recipe and/or performing runtime measurement, for example by scanning (in a single or in multiple scans), reviewing, measuring and/or other operations provided with regard to the specimen or parts thereof using the same or different inspection tools. Measurement results such as measured images are analyzed for example, by employing image-processing techniques. Note that, unless specifically stated otherwise, the terms “inspection”, “metrology” or their derivatives used in this specification are not limited with respect to measurement technology, measurement resolution or size of inspection area.
A variety of metrology tools includes, by way of non-limiting example, scanning electron microscopes (SEM), tunneling electron microscope (TEM), atomic force microscopes (AFM), optical metrology (OCD) and inspection tools, etc.
There is a need in the art to improve the process of metrology, for example by improving the utilization of design data; by improving the preparation of metrology recipes; or by improving the definition of metrology objects and metrology operations used for metrology.